Robert S. Quinn, DMD, MSD, INC. - Specialist in Orthodontics

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	overview
	how orthodontists classify problems

To properly diagnose orthodontic problems, it’s important to consider two factors in combination – the relative position of your teeth, and the shape and position of facial structures. Here’s how professionals assess your treatment needs:

Classification of the Teeth
Bite problems are segmented into three categories – Class I, II or III – depending on the position of the first molars, and the way molars meet during biting motions.

Classification of the Face
It’s not sufficient to categorize orthodontic malocclusions on the basis of a classification of the teeth alone. The relationship with other craniofacial structures must also be considered.

	Classification of the Teeth	Classification of the Face
Class I	BALANCED BITE: A normal relationship exists between the upper and lower teeth and jaws.	A normal craniofacial structure.
Class II	OVERBITE: Class II problems can be due to insufficient growth of the lower jaw, an over-growth of the upper jaw, or a combination of the two. Often, these problems are inherited, but they can be aggravated by environmental factors such as finger sucking. We treat Class II malocclusions with growth redirection that brings upper and lower teeth and jaws into harmony. Examples: Maxillary Dental Protrusion & Mandibular Retrognathism – Jaws (both are displayed at right) The lower first molar rides further back in the mouth than the upper first molar. In this abnormal relationship, the upper front teeth and jaw project further forward than the lower teeth and jaw. There’s a convex appearance in the facial profile, with a receding chin and lower lip. It may be necessary to remove teeth.	Maxillary Dental Protrusion - Teeth This malocclusion may require removal of teeth. Mandibular Retrognathism - Jaws The lower jaw bone has not grown as fully as the upper jaw. This Class II example demonstrates the need for early growth guidance. Maxillary Dental Protrusion - Teeth & Mandibular Retrognathism - Jaws The skeletal disharmony here makes this type of problem more difficult to treat. It may require orthognathic surgery combined with orthodontic treatment.
Class III	UNDERBITE: Class III problems are usually due to an overgrowth in the lower jaw, an undergrowth of the upper jaw, or a combination of the two. Like Class II problems, they can be genetically inherited. Example: The lower first molar is anterior (or more towards the front of the mouth) relative to the upper first molar. In this abnormal relationship, the lower teeth and jaw project further forward than the upper teeth and jaws. In profile, the face displays a concave appearance, with a prominent chin.